Umbilical Hernia

Q. I have been told that my horse has an umbilical hernia. What exactly is an umbilical hernia and what can be done to correct it?

A. A hernia is defined as a "protrusion of an organ or tissue through an abnormal opening." The common hernias affecting the horse involve the herniation of intestine and are inguinal, scrotal, or umbilical in location. The inguinal hernia is created when a piece of intestine slips down the area adjacent to the inguinal canal (the passage, just under the pelvis, that the stalk of the testicles travels from the abdomen to the scrotum) and dissects into the tissue between the hindlegs. The scrotal hernia is formed when the intestine slips down the inguinal canal and goes directly down into the scrotum (the sack of skin that houses the testicles). The umbilical hernia occurs when a piece of intestine protrudes down into a body wall defect in the umbilicus (the navel area).

The development of an inguinal or scrotal hernia is a crisis when the animal shows signs of colic related to the pain of the compressed and obstructed intestine. With an umbilical hernia, there might be no clinical signs because the intestine that is protruding might not be obstructed.

The umbilicus is the lifeline of the developing animal, connecting it to the outside world (and its mother). The umbilical cord contains a vein, two arteries, and the urachus (a tube-like structure that connects to the foal's bladder and empties the bladder into the amnionic sac). The arteries and vein bring blood to or from the placenta. Upon entering the body, the vein goes forward and connects to the foal's blood system via the liver, and the two arteries go up and around the bladder and connect to the foal's blood system.

The area of the abdominal wall surrounding the umbilicus is one of the last areas of the body wall to close during the development of the fetus. If there is any defect in the complete closure of the body wall in this area, it will result in an umbilical hernia. So, a foal can be born with an umbilical hernia, or the hernia can develop during the first week of life. In most foals, if you palpate their umbilical area carefully, you can feel a small (less than the tip of your little finger) defect in the body wall that will disappear as the umbilicus heals. If there is a larger hernia, it can be variable in size (generally between two and 12 centimeters). What you might see, depending on the size of the hernia, is a variable size sack on the underbelly. This is the skin, some subcutaneous tissue, and the intestines! The general method of measuring a hernia is the finger counting method. For example, if three fingers can be inserted into the hernia it is a "three-finger hernia."

It is important to determine that any swelling around the umbilicus is not more than just a small hernia. The hernia should be non-painful, soft, and fluctuant, and you should be able to push the contents of the sack (usually intestines) back up into the abdomen. Given the propensity for the umbilicus to become infected, it is very important to rule this out. If there is any heat, pain, or firm swelling around the umbilical stalk or the foal is even slightly sick, a veterinarian should be called in to check the foal for the presence of infection. Umbilical infection and abscessation can lead to the development of an umbilical hernia in addition to causing severe systemic illness.

There are several treatment options/concerns, the first of which is to do nothing. Many of the smaller hernias are unsightly, but typically don't cause significant problems. A generalization is that hernias smaller than three to four fingers usually will resolve on their own as the foal ages (by 12-14 months). Treatment recommendation for these often includes the daily reduction of the hernia. This simply means pushing the contents of the hernial sack back into the abdomen with your fingers on a daily basis. This allows for the daily determination that the hernia can be reduced and might reduce the risk of the intestines "sticking" within the sack. The risk of intestinal obstruction (and the development of colic) if the intestines become stuck is the major concern; if the hernia can no longer be reduced, surgical correction is considered.

If the hernia is large or the intestine within the sack cannot be reduced, surgical intervention should be considered. In addition, if there is any evidence of umbilical infection/abscess or the presence of a patent urachus (noted by urine leaking from the umbilical stump), surgery might be indicated. Ultrasonography is the most effective way to evaluate the umbilical area for the presence of abnormality. Often, the umbilicus looks quite normal on the outside when infection or an abscess is present within the abdomen. If this is the case, the hernia can be repaired at the same time the umbilical abnormalities are resected.

Other methods of treatment include the clamping of the skin and edges of the defect over the hernia in an effort to scar the tissue together and close the defect without surgical intervention. This technique is reported to be successful, but great care must be taken not to get any intestine included in the clamp. Another method similar to clamping includes the injection of mild blistering agents just under the skin to promote the development of scar tissue and facilitate defect closing. With the blistering technique, great care must be taken not to inject the blister into the intestine or abdominal cavity, which would probably cause the intestine to become stuck in the hernia.

There are two surgical approaches: the open and the closed techniques. The closed technique repairs the hernia without opening the abdominal cavity and has the advantage of simplicity. The closed technique has the disadvantage of not being able to see what is in the hernia sack before suturing it closed--great care must be taken not to place a suture into the intestine. The open technique is the most precise. With the open technique, the hernial sack is opened, evaluated, resected, and the body wall is repaired.

Inguinal hernias often are puzzling. Small hernias in otherwise healthy horses might best be left alone. On the other hand, there always is the possibility of problems whenever intestinal contents are in a hernial sac.

About the Author

Michael A. Ball, DVM, completed an internship in medicine and surgery and an internship in anesthesia at the University of Georgia in 1994, a residency in internal medicine, and graduate work in pharmacology at Cornell University in 1997, and was on staff at Cornell before starting Early Winter Equine Medicine & Surgery located in Ithaca, N.Y. He is also an FEI veterinarian and works internationally with the United States Equestrian Team.

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